Good advice. I had this exact problem with a clogged fuel filter triggering limp mode and a check engine light. I'm glad I had a code reader and access to a filter so we could get back on the road with just a minor delay.
If you can't use the Freightliner program, there are other similar programs through Costco or Motus (formerly Runzheimer). I used the Costco program for our 2015 Grand Cherokee Ecodiesel purchase.